Design and evaluation of a 2 MHz planar inductor boost converter

Abstract

This master’s thesis presents the design, implementation, and experimental evaluation of a high-frequency boost converter operating at a switching frequency of 2 MHz. The converter is developed to supply a piezoelectric actuator driver in a battery-powered lab-on-chip system. Based on predefined specifica tions for input voltage, output voltage, and output power, the boost converter is designed using the LTC7804 controll IC and verified through analytical calculations and LTspice simulations. A key focus of this work is the design and investigation of a custom planar inductor optimized for high-frequency operation. The planar inductor is designed using a four-layer PCB winding in combination with a ferrite core and a defined air gap. Its electrical characteristics are validated through impedance measurements and finite element method simulations, including the analysis of inductance behavior, magnetic flux density, fringing fields, and current distribution. A commercially available wirewound inductor with comparable inductance and DC resistance is selected as a reference. Both inductor implementations are integrated into identical boost converter prototypes and evaluated under the same operating conditions. Simulation and measurement results show that switching losses dominate the overall efficiency at the selected power level and switching frequency, leading to burst mode operation as the most efficient operating regime. The experimental comparison demonstrates that while the planar inductor enables a well-integrated solution with predictable parasitic characteristics, the wirewound inductor exhibits superior high-frequency behavior and slightly higher efficiency margins due to lower parasitic capacitance and higher self-resonant frequency. The results highlight the trade-offs between planar and wirewound inductor technologies in MHz-range boost converters and provide practical insights into the design of high-frequency power converters where size, efficiency, and manufacturability must be carefully balanced